login
This site is supported by donations to The OEIS Foundation.

 

Logo

Annual Appeal: Please make a donation (tax deductible in USA) to keep the OEIS running. Over 5000 articles have referenced us, often saying "we discovered this result with the help of the OEIS".

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A120071 a(n) = n*(n+20). 18
0, 21, 44, 69, 96, 125, 156, 189, 224, 261, 300, 341, 384, 429, 476, 525, 576, 629, 684, 741, 800, 861, 924, 989, 1056, 1125, 1196, 1269, 1344, 1421, 1500, 1581, 1664, 1749, 1836, 1925, 2016, 2109, 2204, 2301 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

REFERENCES

F. P. Muga II, Extending the Golden Ratio and the Binet-de Moivre Formula, March 2014; Preprint on ResearchGate.

LINKS

Table of n, a(n) for n=0..39.

FORMULA

a(n) = (n+10)^2 - 10^2 = n*(n+20), n>=0.

G.f.: x*(21-19*x)/(1-x)^3.

a(n) = 2*n + a(n-1) + 19 (with a(0)=0). - Vincenzo Librandi, Nov 13 2010

MAPLE

seq(sum(4*k-n, k=7..n), n=6..51); # Zerinvary Lajos, Feb 17 2008

MATHEMATICA

s=0; lst={}; Do[s+=n; AppendTo[lst, s], {n, 21, 6!, 2}]; lst (* Vladimir Joseph Stephan Orlovsky, Feb 26 2009 *)

PROG

(PARI) a(n)=n*(n+20) \\ Charles R Greathouse IV, Jan 21 2015

CROSSREFS

a(n-10), n>=11, tenth column (used for the n=10 series of the hydrogen atom) of triangle A120070.

For n*(n+18) see A098850.

Cf. A001477, A098849, A132760, A120061, A132765.

Cf. A132760, A132761, A132762, A098849, A098850, A005563, A028552, A028347, A028557, A028560, A028563, A028566, A028569, A098603, A098847, A132759, A098848. - Vladimir Joseph Stephan Orlovsky, Feb 26 2009

Sequence in context: A041878 A041880 A063319 * A180863 A180857 A168519

Adjacent sequences:  A120068 A120069 A120070 * A120072 A120073 A120074

KEYWORD

nonn,easy

AUTHOR

Wolfdieter Lang, Jul 20 2006

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified December 5 03:30 EST 2016. Contains 278755 sequences.